Cigarette smoking is the single largest preventable cause of disease and premature death in the United States and most smokers begin smoking in early adolescence. With approximately 70 percent of adolescents being seen for medical care each year, the pediatric clinic setting offers a unique opportunity to intervene in the process of initiation and continued cigarette smoking by adolescents. We propose to use pediatric provider-delivered interventions and peer counseling delivered during routine care. This is a relatively untested vehicle for providing smoking prevention and cessation interventions to adolescents. The specific aims of this four year randomized clinical trial are to: (1) refine a provider-delivered office intervention for use in pediatric offices targeting prevention and cessation of smoking in adolescents; (2) develop a peer counseling protocol that can be instituted within a pediatric clinic; and (3) conduct a randomized clinical trial to evaluate the effectiveness of the provider-delivered intervention and peer counseling compared to usual care. Adolescents aged 13 to 17 at study enrollment who are seen in the eight pediatric clinic study sites will be recruited, regardless of smoking status. A total of 300 adolescents per site (2400 across 8 sites) will complete baseline and follow-up assessments. Participating pediatric sites will be randomly assigned to one of two conditions: (1) Special Intervention (SI), consisting of a brief provider-delivered intervention tailored to the stages of smoking initiation of each adolescent, and peer counseling focused on the social aspects of smoking; or (2) Usual Care (UC) control condition. Within the SI sites, all pediatric providers will receive training in the brief provider-delivered smoking prevention and cessation intervention, an office management system will be established to support the provider intervention with adolescents, and peer counselors will provide intervention within the clinics. The main outcome measure will be prevalence of smoking, defined as smoking a cigarette in the last 30 days, at 6- and 12-month assessment in adolescents in the SI compared to the UC condition. Additional outcomes will include adolescents' attitudes, beliefs, and smoking-related behavior, and providers' knowledge, attitudes, and practice behaviors. Development of effective provider-delivered and peer counseling programs for prevention and cessation of smoking among adolescents has broad applicability for this important public health problem. Pediatric clinic visits present an excellent opportunity to reach a large number of adolescents. The use of peer counselors within this setting, with their potential to address the difficult social issues related to smoking among adolescents, is a novel and potentially powerful approach to the prevention and cessation of smoking by youth.